In general, a seat belt is a primary safety device to protect a driver and passenger(s) from any abrupt traffic accident. In light of such importance, the fastening of seat belts is now mandatory under the many current traffic laws. To this end, a device to prevent the start of an engine without fastening of a seat belt has been under development.
As illustrated in FIG. 1, a seat belt assembly is shown where a seat belt retractor 10 is installed within the lower side of a center pillar of a car body, and the seat belt 11, coupled with the seat belt retractor 10, is inserted into the upper part of an anchor plate. When the tongue of the seat belt is inserted into the buckle of the seat belt, a person is fastened into the seat belt.
The seat belt 11 can be fastened with a slow pulling, but sudden rapid pulling cannot release the seat belt, due to the emergency locking retractor.
Further, after fastening the seat belt, the belt begins to retract slightly within the retractor, and adjust tightly to the human body. Thus, the belt presses across the user's upper body, and he feels some discomfort on the fastening of the seat belt.